VMMC VMMC Medical Solved Paper-2011

  • question_answer
    The resultant of two rectangular simple harmonic motions of the same frequency and unequal amplitudes but differing in phase by \[\frac{\pi }{2}\] is

    A)  simple harmonic             

    B)  circle    

    C)  ellipse                 

    D)         figure of eight

    Correct Answer: C

    Solution :

                            If first equation is \[{{y}_{1}}={{a}_{1}}\sin \omega t\] \[\Rightarrow \]               \[\sin \omega t=\frac{{{y}_{1}}}{{{a}_{1}}}\]                                        ?(i) Then second equation will be \[{{y}_{2}}={{a}_{2}}\sin (\omega t+\pi /2)={{a}_{2}}\cos \omega t\] \[\Rightarrow \]               \[\cos \omega t=\frac{{{y}_{2}}}{{{a}_{2}}}\]                                       ?(ii) By squaring and adding Eqs. (i) and (ii), we get \[{{\sin }^{2}}\omega t+{{\cos }^{2}}\omega t=\frac{y_{1}^{2}}{a_{1}^{2}}+\frac{y_{2}^{2}}{a_{2}^{2}}\] \[\Rightarrow \]               \[\frac{y_{1}^{2}}{a_{2}^{2}}+\frac{y_{2}^{2}}{a_{2}^{2}}=1\] This is the equation of ellipse.


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